Alexander Behm created SPARK-22073:
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Summary: Add workaround for HIVE-15653 to avoid stats being
accidentally wiped
Key: SPARK-22073
URL: https://issues.apache.org/jira/browse/SPARK-22073
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 2.2.0
Reporter: Alexander Behm
The alterTable() RPC to the Hive Metastore has the subtle and undesirable
side-effect of sometimes wiping/recreating useful stats like 'numRows' and
'totalSize'.
Further, the alterTable() causes extra "hidden" load on the
NameNode/S3/whatever to list all the files and get the 'totalSize' and
'numFiles'.
This behavior can lead to confusion, e.g., if a SparkSQL query suddenly becomes
slow due to a bad plan because somebody ran an unrelated ALTER TABLE from
Hive/SparkSQL which wiped the stats (not fun to do the RCA).
One way to avoid this problem is to always add a special table property
DO_NOT_UPDATE_STATS to the altered table before doing the alterTable() RPC to
the Metastore.
See HIVE-15653 for more details.
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